1. Field of the Invention
The present invention is related to a double frequency signal generator. More particularly, the present invention is related to a double frequency signal generator in which a double frequency signal may be provided with presence of a synchronization signal having a duty cycle of 1% to 99% as an inputted signal.
2. Description of the Related Art
A conventional integrated chip (IC)-based double frequency signal generator is shown in FIG. 1. The double frequency signal generator 1 is composed of an IC and several electronic components. Through the IC-based double frequency signal generator 1, an input signal is conversed to an output signal having a frequency double that of the input signal. However, since the IC-based double frequency signal generator 1 involves the IC, a cost burden is generally taken place when a plenty of such double frequency signal generators are required.
To resolve the high cost issue of the above IC-based double frequency circuit, an analog double frequency circuit has been suggested. Referring to FIG. 2, a schematic diagram of a conventional analog double frequency circuit 2 is shown therein. In the analog double frequency circuit 2, a square-wave signal having a duty cycle of 50% is inputted. Then, the square-wave signal is use for triggering at positive and negative edges and thus a double frequency signal is generated. However, the input signal has to be strictly limited to a square-wave signal having a duty cycle of 50%. If any error takes place on the input signal, the generated signal may not be an exact double frequency signal. Thus, this kind of double frequency generator is not significantly ideal and practicable.
From the above discussion, it can be readily known that such conventional double frequency signal generator is inherent with some drawbacks and needs to be addressed and improved.
In view of these problems encountered in the prior art, the Inventors have paid many efforts in the related research and finally developed successfully a double frequency signal generator, which is taken as the present invention.